The fire protection systems in warehouses at Hill, Kelly, McClellan, Robins, and Tinker Air Force Bases were studied. Twelve different sprinkler system configurations were analyzed using a numerical technique, and the performance of the systems after being retrofitted with 0.64-in orifice sprinkler heads was predicted. The numerical results for buildings 380 and 385 at Robins Air Force Base and for buildings 10, 18 and 412 at Tinker Air Force Base were used as the standard reference values in determining whether or not other systems would give adequate protection when retrofitted with the 0.64-in. orifice heads. The results are reported.